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# Cefriaxone (ceftriaxone)
## Overview
A third-generation cephalosporin providing broad-spectrum coverage against Gram-positive (including *Streptococcus* spp.) and Gram-negative organisms (including *Neisseria* and *Haemophilus*). It has an exceptionally long half-life, allowing for once-daily dosing.
## Primary Indications
* Community-acquired pneumonia
* Meningitis
* Gonococcal infections
* Complicated intra-abdominal infections
* Pyelonephritis and complicated UTIs
* Skin and soft tissue infections
* Prophylaxis for surgical procedures
## Adult Dosing
* **Standard Infections:** 1–2 g IV/IM every 24 hours.
* **Meningitis:** 2 g IV every 12 hours.
* **Gonorrhea:** 500 mg IM as a single dose (patients <150 kg); 1 g IM for patients ≥150 kg.
* **Max Dose:** Generally 4 g/day, though 2 g/day is standard for most indications.
## Pediatric Dosing
* **General Infections:** 50–75 mg/kg/day IV/IM administered once daily.
* **Meningitis:** 100 mg/kg/day IV divided every 12 hours (initial dose 100 mg/kg, max 4 g/day).
* **Gonorrhea:** 25–50 mg/kg IV/IM (max 500 mg) as a single dose.
* **Neonates:** 50 mg/kg/day once daily.
## Dose Adjustments
* **Renal Impairment:** No adjustment required in patients with renal impairment.
* **Hepatic Impairment:** No adjustment required; however, monitor closely if concurrent severe renal impairment exists.
* **Combined Impairment:** Maximum dose 2 g/day.
## Contraindications
* Hypersensitivity to cephalosporins or severe hypersensitivity to penicillins.
* **Neonates (≤28 days):** Contraindicated in neonates receiving calcium-containing IV solutions (including parenteral nutrition) due to risk of fatal ceftriaxone-calcium precipitates in the lungs and kidneys.
## Adverse Effects
* **Common:** Injection site reactions (pain/induration), diarrhea (including *C. difficile*), eosinophilia, thrombocytosis.
* **Serious:** Biliary sludge/pseudolithiasis (ceftriaxone-calcium precipitates), hemolytic anemia, anaphylaxis, *C. difficile*-associated diarrhea.
## Key Drug Interactions
* **Calcium-containing products:** Do not administer via IV lines containing calcium in neonates; in adults/older children, flush lines thoroughly between doses.
* **Anticoagulants:** May increase the effect of vitamin K antagonists (e.g., warfarin).
* **Probenecid:** Does not significantly affect ceftriaxone renal clearance.
## Monitoring
* **Clinical:** Resolution of infection, site of administration (thrombophlebitis).
* **Labs:** Periodic CBC (if prolonged therapy >10 days), renal/hepatic function.
* **Special:** Monitor for gallbladder symptoms if prolonged therapy or biliary sludge is suspected.
## Clinical Pearls
* **Spectrum:** Not active against *Enterococcus* spp., *Pseudomonas aeruginosa*, or MRSA.
* **Administration:** IM injections should be reconstituted with 1% lidocaine to reduce pain if allowed by local protocol/clinical guidelines.
* **Biliary Issues:** Ceftriaxone is highly protein-bound and concentrated in the bile; "biliary pseudolithiasis" is usually reversible upon discontinuation.
* **Local Protocols:** Always verify institutional guidelines for specific indications, as empiric therapy depends heavily on local antibiograms.
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*Disclaimer: This information is for educational purposes only and does not constitute medical advice. Clinical protocols vary by institution. Always verify dosages, contraindications, and drug interactions against the most current product labeling, institutional formulary, or clinical decision support systems before prescribing.*
